Break a leg!

Break a leg is an expression that does not translate literally into French. However, they do have their own - "bonne merde," or "good shit". You tell someone "bonne merde" before a performance, before a huge exam. More or less the same situtations as "break a leg". Apparently the expression comes from back in the day when people rode carriages to go to the theater. Those putting on a play would wish eachother "bonne merde" because the more poop there was in front of the theatre, the more horses there were, the bigger audience there was. So good shit to you all!